Echelon i.LON 100 e2 Internet Server - Manual (Page 138)

i. LON 100 Internet Server Programmer’s Reference 9-1
9 Analog Function Block
You can use Analog Function Blocks to perform a variety of statistical operations on the
values of the data points in your network, and store the result of each operation in an output
data point. You can perform these operations on as many input data points as you like per
Analog Function Block. The operations you can perform on them include determining the
average value of the input data points, the maximum value of the input data points, the
minimum value of the input data points, the sum of the input data point values, and several
others. Each operation is described in detail later in this chapter.
You can also select a comparison function as your operation. In this case, the Analog
Function Block will compare the value of all the input data points to the value of a data point
selected as the compare data point. You can choose from a variety of comparisons that an
Analog Function Block can perform between the data points, including Greater Than, Less
Than, and Equal To. The Analog Function Block will compare the values of the compare and
input data point using that comparison, and update the output data point to a True or False
value based on the result of that comparison.
If you are using a comparison function, and your Analog Function Block has multiple input
data points, you can specify a percentage. If that percentage of the comparisons between the
input and compare data points returns True, the output data point will be set to True.
Otherwise, it will be set to False.
For example, consider a case where an Analog Function Block has five input data points and
is using Greater Than as the comparison function. Assume that the percentage is set to 50%.
If the value of the 50% (at least three) of the input data points is greater than the value of
the compare data point, the output data point will be set to True. Otherwise, it will be set to
False.
The Analog Function Block will perform the operation you have selected for it each time any
of its input data points are updated, or at a timed interval you specify. You could use these
calculated values as a part of a control system or to monitor alarm conditions based on
multiple inputs.
NOTE: Analog Function Blocks are not supported by, and can not be configured with, the
i. LON 100 Configuration Software.
9.1 AnalogFB.XML
The AnalogFB.XML file stores the configuration of the Analog Function Blocks that you have
added to the i. LON 100. You can create up to 20 Analog Function Blocks on your i. LON 100.
Each Analog Function Block is signified by an element in the XML file. You can
create Analog Function Blocks with the AnalogFBSet function, or by manually editing the
AnalogFB.XML file and downloading it to the i. LON 100 via FTP. The sections following this
example provide instructions and guidelines to assist you when doing so.
The following represents a sample AnalogFB.XML file for an
i. LON 100 with one defined
Analog Function Block. This Analog Function Block determines the maximum value between
two data points, NVL_nviClaValue_1 and NVL_nviClaValue_2, and stores that value in the
value field of a data point called NVL_nvoClsValue_1.
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